1. Field of the Invention
The invention relates generally to arc lamps, and specifically to the electronic control and power supply systems used with xenon arc lamps.
2. Description of the Prior Art
Short arc lamps provide intense point sources of light that allow light collection in reflectors for applications in medical endoscopes, instrumentation and video projection. Also, short arc lamps are used in industrial endoscopes, for example in the inspection of jet engine interiors. More recent applications have been in color television receiver projection systems.
A typical short arc lamp comprises an anode and a sharp-tipped cathode positioned along the longitudinal axis of a cylindrical, sealed concave chamber that contains xenon gas pressurized to several atmospheres. U.S. Pat. No. 5,721,465, issued Feb. 24, 1998, to Roy D. Roberts, describes such a typical short-arc lamp. A typical xenon arc lamp, such as the CERMAX marketed by EGG/ILC Technology (Sunnyvale, Calif.) has a two-legged strut system that holds the cathode electrode concentric to the lamp's axis and in opposition to the anode.
As a xenon arc lamp ages, it either will fail to ignite or not ignite properly. Lamp output can also diminish due to blackening inside the glass envelope. It is therefore useful to provide operators with warning and status indicators that can help keep the lamps running at their best.
The power supplies for xenon arc lamps also need to monitor the output voltage and current that they are delivering to the lamp so that automatic shutdowns can be done when the lamp develops a fault. Since cooling is so critical, the health of the forced air cooling fan needs to also be monitored through the availability of electrical power to the fan.